I Got the 2 DLC(Ryder White and Bloodbath Arena) for dead island,but when are they available for me to play?
Do I have to complete the game or get to a specific locations?
All new blueprints and weapons are added to your game with the install of the DLC.
According to the Dead Island Wiki, this DLC was released on February 1, 2012.
As you can clearly see in this video, you can access this content by selecting Ryder White at the character select screen at the start of a new campaign.
Bloodbath Arena as described on the Dead Island Wiki states: